Process of exhausting lamps.



J. T. MARSHALL, DECD.

E. T. MARSHALL, EXECUTRIX.

PROCESS OF EXHAUSTING LAMPS.

APPLICATION FILED ocT.23. I911.

1 05,002. Patented Nov. 14, 1916.

Witnesses:

' Inventor: v Jphn T. marshal I, deceased.

Ehza T. marshal I, executrix,

M M Y by M DIttorneg UNITED STATES, PATENT OFFICE.

JOHN T. MARSHALL, DECEASED, LATE OI METUCHEN, NEW JERSEY, BY ELIZA '1. MARSHALL, EZECUIBIX, OF METUC'HEN, NEW JERSEY, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

rnocnss or nxrmusrme LAMPS.

Specification of Letters Patent.

Patented Nov. 14, 1916.

Application filed October 23, 1911. Serial No. 858,178.

To all whom it may concern:

Be it known that JOHN T. MARsHALL, deceased, late a citizen of the United States and a resident of Metuchen, in the county of Middlesex, State of New Jersey, during his lifetime invented certain new and useful Improvements in Processes of Exhausting Lamps, and that I, ELIZA T. MARSHALL, executrix under the. last will and testament of the said JOHN T. MARSHALL, do hereby declare, to the best of my knowledge and belief, that the following specification, taken in connection with the accompanying drawing, is a clear, true, and complete description of said improvements.

This invention relates to the production of evacuated vessels in which a high degree of vacuum is desired, and more particularly to exhausting incandescent lamps.

en a number of incandescent lamps, particularly metal filament lamps, are 'ex= hausted in the usual way, the finished lamps differ considerably in voltage; that is, in the amount of voltage which must be applied to the lamp to cause it to give the candle power for'which it was designed. Apparently these variations in voltage are caused to a large extent by heating the filament in the presence of the gases and vapors which are necessarily present as long as the lamp is connected to the pump.

One object of the present invention is to produce an improved process of exhausting which will' decrease the difiiculties of this kind heretofore encountered.

A further object is to produce the desired vacuum in an incandescent lamp without heating the filament while the lamp is connected to the pump.

A still further object is to regulate more exactly than heretofore the amount of phosphorus vapor evolved in the lamp or vessel which is being exhausted; and in general to improve the production of incandescent lamps and similar evacuated vessels.

To accomplish these objects phosphorus or similar vapor is evolved directly in the lamp or vessel after the lamp has been sealed and is entirely finished so far as glass working is concerned. Thevapor may be evolved in a vessel or lamp in various ways, but preferably the phosphorus, or some substance which is capable of evolving the desired vapors when heated, is

placed inside the vessel or lamp in such a relation to the filament or other current carrylng portion of the lamp that when the lamp is sealed off and then lighted at the proper voltage to produce the blue glow, phosphorus vapor is evolved by the heat of the lighted filament, the blue glow disappears, andthe vacuum is perfected. The amount of phosphorus introduced into the lamp is controlled very exactly by dipping the mount of each lamp into a solution, or liquid containing suitable material, such as phosphorus. dipped to the .same extent, while the strength of the solution is kept uniform, and enough of the liquid adheres, especially to the metal. of the mount to produce the necessary amount of phosphorus vapor in the lamp bulb when the'lamp is lighted. To vary the amount of phosphorus introduced into each lamp the depth of immersion or the strength of the solution may be varied.

The present invention will best be understood in connection with the accompanying drawing, which merely for purposes of illustration shows an incandescent lamp at different stages of the process invented by him, and in which Figure 1 shows the mount being dipped into a solution of some substance which will evolve phosphorus vapors when heated; Fig. 2 shows the lamp as connected to the pump, the mount having been coated at the bottom by being dipped, the coating being much exaggerated in order that it may be visible; and Fig. 3 shows the lamp after having been sealed off from the pump and before being lighted for the first time.

In accordance with the present invention there is placed in a vessel or a lamp 1 which is to be exhausted some vapor generating substance, such as phosphorus,

which generates when heated a vapor which reacts with the residual atmosphere of the lamp and is capable of improving the lamp and perfecting a partial vacuum. The

Preferably each mount is.

ation of vapor, as the filament is not heated while the lamp is on the pump. When the vacuum is as high as is usually obtained by. pumping-when exhausting in the usual way, the lamp or vessel is sealed off at 3 close to the bulb. This operation removes the tubulature and is the last glass-working operation performed on the lamp, which is now finished so far as glassworking is concerned. No portion of the tubulature or any other projection which contained phosphorus must afterward be cut off, as in the customary method of exhausting where phosphorus paint is placed in the tubulature and none of the glass of the lamp need afterward be heated high enough to drive out of it occluded gases or water vapor.

The vacuum produced by umping is not high enough and is perfected by generating in the lamp or vessel from the vapor generating substance, such as phosphorus some vapor which will react with the residual atmosphere in the presence of the highly incandescent filament and perfect the vacuum, or in some way improve the lamp. This substance, usually some form of phosphorus, may be heated by the filament to generate vapor. In the preferred construction the vessel to be evacuated contains a high resistance conductor, and the vapor generating substance is placed on or in thermal relation to the conductor so that when suflicient current is passed through the conductor the substance will be heated suificiently to evolve thevapor.

In exhausting incandescent lamps, the phosphorus vapor is preferably introduced by placing the vapor enerating substance on the mount, which is lnside the lamp when the lamp is finished and which comprises the metal filament 4., preferably of tungsten,

and its supports, such as the glass post 5 and metal anchor or supports 6. This substance is placed on some metal part of the mount in thermal relation to the filament 4 so that lighting the lamp at a voltage which produces a blue glow in the bulb will heat the substance and cause the phosphorus vapor to be generated. This vapor acts as in the usual method of exhausting, and in its presence the blue glow disappears and the vacuum is perfected.

The vapor generating substance may be placed upon the mount in various ways, but preferably the mount is dipped into a liquid containing the substance, then withdrawn, and 'the adhering liquid permitted to dry. Practically the whole mount may be immersed in the liquid, wetting the filament and supports, or it may be dipped until only the lower end of the post 5 and the lower metal anchors or supports 6 are immersed, as shown in Fig. 1. The same amount of phosphorus is introduced into each lamp by dipping each mount to a uniform depth into a bathor solution of phosphorus, of which the strength is kept uniform. A bath of phosphorus of such a strength that it produces a barely discernible deposit upon'the glass of the mount after the adhering liquid has dried is suflicient to perfect the vacuum. The amount of phosphorus introduced into the lamp may be controlled very exactly by varying the strength of the bath or solution or by varying the depth of immersion. This method of introducing phosphorus or similar material into a, lamp or vessel may be .used to advantage in any method of exhausting which requires the introduction of such material.

Although the mount is preferably dipped .porize from the metal to remove the blue glow and perfect the vacuum in the presenceof the intensively incandescent filament, without heating the glass of the lamp enough to drive out of it any occluded gases or water vapor.

This invention may be embodied in many other forms than that shown and described and is not limited to the precise arrangement disclosed herein, since various modifications thereof will suggest themselves to those skilled in the art without departing from the spirit ofthe invention, the scope of-which is set forth in the annexed claims.

What is claimed as new and desired to be secured by Letters Patent of the United States, is

1. In the manufacture of an incandescent lamp having metal parts comprising a tungsten filament andmetal anchors for the filament, the process which consists in applying to metal parts of the mount in position to be vaporized by the heat of the incandescent filament a substance solid at room temperature but reacting with the residual atmosphere to improve the lamp when vaporized in the presence of the incandescent filament, exhausting the lamp without heating the filament, sealing off the lamp, and then for the first time passlng 'current through said filament to vaporize below the temperature at which occluded 13o gases are driven "out of it.

2. In the manufacture ofan incandescent lamp having metal parts comprising a tungsten filament and metal supports for the to a predetermined degree 'heat of the incandescent filament, exhausting the lamp without heating the filament, sealing off said lamp, and subsequently raising said filament to intensive incandescence to vaporize'the phosphorus while all the 'glas'sof the lamp is below the temperature at which occluded gases are driven out of it. 3

3. In the manufacture of an incandes cent lamp having a mount comprising a metal filament and metal anchors, the process which consists in wetting the metal of the mount to a predetermined extent with a liquid having uniformly distributed through it a definite percentage, of a substance solid at room temperature and'vaporizable by incandescence of the filament, drying'the metal to leave on it a coating of the solid substance, exhausting the lamp containing the coated metal without heating said filament, sealing olf the lamp and then for the first time passing current through said filament to vaporize said substance and raise said filament to intensive incandes cenc conjunctively with the generation of said vapor while the glass of the lamp is below the temperature at which occluded gases are evolved.

. 4. In exhausting incandescent lamps, having mounts comprising metal filaments and metal anchors, the steps of introducing the same amount of phosphorus into each lamp by dipping the of all the mounts to the same extent into a liquid having phosphorus uniformly distributed through it, drying themetal parts to leave a coating of phosphorus on them, pumping out the lamp without heating the filament, sealing off the lamp, and then for the first time passing current through the filament and raising it to intensive incandescence.

5. The steps in the manufacture of a tungsten filament incandescent lamp which consist in coating atleast a part of the tungsten filament with a substance solid at room temperature and reacting with the atmosphere in the lamp when vaporized in the presence of the incandescent filament to improve the lamp, exhausting and sealing off the lamp without vaporizing said solid substance, and then for the first time passing current through the filament to vapori ze said substance and render said filament intensively incandescent inv the vapor of said substance while the glass of the lamp is below the temperature at which occluded gases and water vapor are driven out of it.

In witness whereof, I have hereunto set my hand this seventeenth day of October,

ELIZA T. MARSHALL, I Ewecuh'iw of the estwteof J ohm, T. arshall,

deceased. Witnesses:

JOHN, W. HOWELL, JENNIE STEED.

corresponding metal parts 

